1. Field
Although not so limited in its utility or scope, implementations of the present invention are particularly well suited for incorporation in material sortation systems such as those used in moving mail pieces through various stages of processing in a mail processing facility, for example, and, in particular, in conjunction with a roller conveyor.
2. Brief Description of an Illustrative Environment and Related Art
Material handling operations frequently involve the use of transport systems including networks of conveyor belts and roller conveyors. In a typical conveyor system, a primary roller conveyor extending along a first axis can have one or more secondary belt or roller conveyors adjacent thereto and in transporting communication therewith. Various apparatus have been previously employed for facilitating the automated transfer or diversion of articles from a primary roller conveyor to a secondary conveyor or a receptacle adapted for collecting the articles being conveyed, for example.
A traditional set of transfer apparatus used in combination with a section of primary roller conveyor is capable of transferring conveyed articles to another, secondary conveyor that moves articles in a direction orthogonal to the direction of conveyance of articles on the primary conveyor. In order to reduce wear and potential impact damage to articles being orthogonally transferred, an elevatory right-angle transfer device temporary lifts an article being transferred above the plane defined by the tops of the rollers in the direction transition region of the primary conveyor and then transfers the article to the adjacent, orthogonally extending conveyor. Many extant transfer apparatus perform the lifting and transfer operations with distinct mechanisms. For example, an electric or pneumatic lift mechanism lifts the article and a transfer mechanism engages and moves the article to the adjacent conveyor.
At least one attempt at combining lifting and right-angle moving operations employs a plurality of composite chains that are moved along planes extending between adjacent rollers carried by a section of roller conveyor with which the device cooperates. As explained in the abstract of U.S. Pat. No. 5,699,892 to Shyr et al., each composite chain, which is driven by a driving sprocket, “is formed by combining a regular chain with a roller chain which has a plurality of free rollers to an outer side thereof. Each composite chain is located between two adjacent rollers of the roller conveyor with the free rollers movable to be higher than the conveyance surface of the conveyor while the regular chain (is) lower than the conveyance surface so that when the motor drives . . . the chains via the sprockets, the free rollers are moved to be higher than the conveyance surface to contact and raise a conveyed article . . . thus achieving the shifting operation including vertically elevating and horizontally moving.”
Although the device described in U.S. Pat. No. 5,699,892 appears to address various shortcomings of previous orthogonal transfer devices, it may not be suitable for the transfer of certain articles. For example, cardboard containers and even some plastic bins, if sufficiently weighted, may be damaged by the free rollers of the composite chain. Furthermore, the composite chains undoubtedly add to the weight and expense of the device. Moreover, the movement of numerous composite chains of the type described in the '892 contributes to the overall noise level of the material handling environment in which they are used.
In addition to the orthogonal transfer of articles, conveyor systems often required the diversion of articles at angles of less than 90 degrees (e.g., 30° and 45° are two of the most common diversion angles). As with 90-degree transfer apparatus, various devices have been previously developed for the diversion of articles to adjacent branch conveyors. Traditionally, however, two different types of apparatus have been used at transfer and diversion junctions.
Accordingly, there exists a need for a simplified directional transition module that can accomplish package lift and transfer and diversion using a single set of like mechanisms as opposed to a first set of mechanisms for accomplishing package lifting and a second set of mechanisms to accomplish package transfer.